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Fast idle wax unit replacement

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The cooler temps are upon us and my bike now struggles to reach fast idle, it can take up to a minute to settle. Is that the telltale of a failing wax unit? Last year I removed the airbox to inspect my vacuum lines and found the rubber seal that's around the wax unit rod to be torn, though it operates its full range of motion.

 

Provided a new unit is on the way, what's the procedure to adjust the nut on the rod? I see that this part was adjusted at the factory when assembling the bike and shouldn't be messed with, but what about a new part?

 

Thanks,

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Before you blame the wax-core warm up unit as the (sole) cause for your bike's poor start-from-cold you should ask yourself: Have the non-VTEC valve clearances ever been checked/adjusted?  Tight non-VTEC valve clearances can cause poor starting characteristics.  What is the condition of the spark plugs?  Are they original to the bike?  Old spark plugs that are in the last half of their useful lifespan can cause poor starting characteristics.   

 

As part of my refurbishment efforts on my '01 VFR800 I replaced the fast-idle wax-core unit, just opened up the assembly that the unit goes inside of, removed the old unit, installed the new one and put things back together.  No need to change any of the factory "white paint" marked items.

 

Yeah, wax-core units don't live forever, they slowly lose their original range of motion, there's a lot of variation in longevity with something like a wax-core unit, some individual examples come off the production line at the high quality end of the spectrum and they last longer than others produced right along with the good ones, but there's a reasonable lifespan you can expect from this sort of thing and it seems like 20 years is "great" and slightly less is "good" and less than that is "fair".  But whatever, the wax-core unit isn't hard to replace.

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Also make sure that the orifice on the top of the thermostat housing that supplies the coolant to the wax unit is not blocked.

It is small, and because it sits on top it often fills with gunk if any air has been in the cooling system. 

It happened to mine and also my mates Blackbird. 

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The spark plugs are new from last year, they were in bad shape and replacing them literally transformed the bike.

 

Is there any benefit in first changing the coolant? It is on my to-do-list as I haven't changed it in years, perhaps it's worth doing that before messing with the wax unit.

 

With regards to the core itself, is it a separate part from the whole assembly part number 16044-MCW-003?

 

Thanks guys,

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If the bike is "struggling to reach fast idle" when first started then I doubt you have any coolant flow issue. When the bike is cold the wax unit will also be cold, and at that time is will be in it's cold extended position. If there was any coolant blockage the unit would be slow to reduce the fast idle back to a normal warm speed. I would be taking a look at the wax unit and the movement of the starter valves to ensure that the starter valves are being held open when cold. If the starter valves themselves are out of whack that won't be helping. 

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3 hours ago, Terry said:

If the bike is "struggling to reach fast idle" when first started then I doubt you have any coolant flow issue. When the bike is cold the wax unit will also be cold, and at that time is will be in it's cold extended position. If there was any coolant blockage the unit would be slow to reduce the fast idle back to a normal warm speed. I would be taking a look at the wax unit and the movement of the starter valves to ensure that the starter valves are being held open when cold. If the starter valves themselves are out of whack that won't be helping. 

Terry, doesn't the wax core expand when heated, and contract when cold?

 

Unless you're skipping part that in your explanation and jumping forward to the part where the contracted wax core pulls on the starter valve control mechanism which holds it open, and when the wax core warms and expands it relaxes its pulling on the mechanism.  

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11 minutes ago, GreginDenver said:

Terry, doesn't the wax core expand when heated, and contract when cold?

Actually Greg you are probably correct but the manual is not that easy to figure. Looks like the WU connects and pulls the SV open for cold, then releases them for hot, so shorter cold/longer hot seems more likely from closer inspection. The key in any case is to check whether the SV's are being lifted when cold and set down when hot, which is easy enough to visually spot.

 

image.thumb.png.5655b70efd66aa0e9d2768d968e38ab4.png

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You're actually right Terry, The problem with mine and my mates was high idle after getting hot. Not slow idle while cold.

I've also noticed US bikes seem to have a lot more corrosion than Oz bikes.

Not much rain here, and definetly no salt in winter.

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6 hours ago, Terry said:

Actually Greg you are probably correct but the manual is not that easy to figure. Looks like the WU connects and pulls the SV open for cold, then releases them for hot, so shorter cold/longer hot seems more likely from closer inspection. The key in any case is to check whether the SV's are being lifted when cold and set down when hot, which is easy enough to visually spot.

 

image.thumb.png.5655b70efd66aa0e9d2768d968e38ab4.png

Here's a short video somebody made explaining the wax unit on a 6th Gen VFR:

https://www.youtube.com/watch?v=k4oVVbzTvVo

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The whole thing is just goofy in my opinion. Instead of adding a couple lines of code to their ECU, they add two coolant hoses and a wax actuator.

 

I capped the nipples supplying water to mine and installed a manual choke cable which is virtually unnecessary in warm weather. 

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Could a faulty air temp sensor or water temp sensor cause my lazy start issue in cold weather? I can get the motor to reach fast idle with a few cracks of the throttle, but something's definitely up... aside from that the engine idles nice and steady when hot and throttle modulation on/off is great, it really is a problem when cold. I know it's a minor annoyance, I just like my toys to work well...

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38 minutes ago, Bruckner said:

Could a faulty air temp sensor or water temp sensor cause my lazy start issue in cold weather? I can get the motor to reach fast idle with a few cracks of the throttle, but something's definitely up... aside from that the engine idles nice and steady when hot and throttle modulation on/off is great, it really is a problem when cold. I know it's a minor annoyance, I just like my toys to work well...

Air Temp Sensor is purely that, ambient air temperature and has no controlling input. The ECT, engine coolant sensor is a two part device one part to your Instrument Panel coolant temp, and the other to the ECM.

The ECT can cause cold start issues But, If you're getting good engine performance and throttle control and no Fi codes for the ECT (Code 7) then you'd assume it's probably O.K.

As someone else said, the Wax unit doesn't last forever, you said you have a new one on order so hopefully that will fix the issue.

It appears the wax unit is no longer acting on the Starter Valves as it should do when cold. As Terry mentioned, with the air box removed you should be able to visually see the wax unit operating or not.

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On ‎9‎/‎11‎/‎2019 at 8:46 AM, Bruckner said:

The spark plugs are new from last year, they were in bad shape and replacing them literally transformed the bike.

 

 

I ran one set of plugs 56,000 miles(they were shot disintegrated), and made no difference in performance, which was already flawless, I just knew they had 56,000 miles and needed to come out. 

 

So I wonder if you have some kind of fueling contamination issue, as to why plugs transformed the bike.

 

 

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I was having issues with cold starting and no high idle, so I replaced my fast idle wax unit - lubricated my linkages and re-synced the starter valves.

After replacement, zero change in the characteristics of he bike. So I decided to turn the "non-adjustable" nut on the fast idle wax unit by 3 turns. Made the world of difference.

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But... it's non-adjustable! That's as bad as tearing the tag off a mattress! 

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On 10/28/2019 at 3:26 PM, Marvelicious said:

But... it's non-adjustable! That's as bad as tearing the tag off a mattress! 

haha, NEVER tear the mattress tag! those legal authorities will be after you in a heart beat!

 

 

My theory on the wax unit is over time the bushings and little plastic grommets in the linkages wear down and slowly allow the valves to not be as open as they would normally be. Essentially compensating for a horrible design! my 1995 VW golf with a single port fuel injector had a much more sophisticated starting system.....Electronically controlled!

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If I had mad fabrication skills (which I do not . . .   ) I would get a starter valve manual control and cable from a 98 or 99 and adapt it to my 6th gen and ditch the wax unit.  On my 99 I've always liked that I could use it to control the idle speed when at high(er) altitude.   Maybe in another life . . .

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10 hours ago, Cogswell said:

If I had mad fabrication skills (which I do not . . .   ) I would get a starter valve manual control and cable from a 98 or 99 and adapt it to my 6th gen and ditch the wax unit.  On my 99 I've always liked that I could use it to control the idle speed when at high(er) altitude.   Maybe in another life . . .

I have wondered if anybody ever did the conversion....... I do like my fast idle lever on my 5th gen.

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Just in case anyone was curious.... this is how a cold bike sitting for 3 weeks starts with a semi dead battery at 1 degree Celsius (34F) with the fast idle was nut adjusted to 3 turns.

 

It will rev up to 2000 rpm until the cold oil gets flowing then up to 2300 rpm until a coolant temperature of about 44C (111F) where it slowly comes down until the temp reaches 60C (140F) where the rpms will go back to the normal 1200 rpm idle.

 

And, yes, even before the swap it was this slow to start in the cold especially after sitting so long. I should also mention, the idle when cold used to be around 800-900 rpm

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I ended up postponing the installation of my new fast idle device, as the winter nears with ever colder mornings what I noticed is that the wax unit works as it should... when it is near freezing outside! I mean, it'll fire up and go straight to fast idle, where as mild fall season temps will produce a lazy start with fast idle creeping up over a 10-15 seconds. My theory is that a tired wax unit will not retract fully when cooling down in mild temps... bike is now in storage, will deal with this in the spring which won't come soon enough!

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